Vibration as an exercise modality: how it may work, and what its potential might be

Whilst exposure to vibration is traditionally regarded as perilous, recent research has focussed on potential benefits. Here, the physical principles of forced oscillations are discussed in relation to vibration as an exercise modality. Acute physiological responses to isolated tendon and muscle vibration and to whole body vibration exercise are reviewed, as well as the training effects upon the musculature, bone mineral density and posture. Possible applications in sports and medicine are discussed. Evidence suggests that acute vibration exercise seems to elicit a specific warm-up effect, and that vibration training seems to improve muscle power, although the potential benefits over traditional forms of resistive exercise are still unclear. Vibration training also seems to improve balance in sub-populations prone to fall, such as frail elderly people. Moreover, literature suggests that vibration is beneficial to reduce chronic lower back pain and other types of pain. Other future indications are perceivable

Phonon limited thermoelectric transport in Pb

We present a fully ab initio based scheme to compute transport properties, i.e. the electrical conductivity {\sigma} and thermopower S, in the presence of electron-phonon interaction. Therefore, we explicitly investigate the k-dependent structure of the Eliashberg spectral function , the coupling strength, the linewidth and the relaxation time {\tau}. We obtain a state-dependent {\tau} and show its necessity to reproduce the increased thermopower at temperatures below the Debye temperature, without accounting for the phonon-drag effect. Despite the detailed investigations of various k and q dependencies, the presented scheme can be easily applied to more complicated systems.Comment: 9 pages, 10 figures, supplemental material adde

Vibration and bone – an option for long-term space missions?

Bone is lost during sojourns in microgravity. In order to prevent fractures in future manned inter-planetary missions, efforts are currently being made to develop effective countermeasures. Bones adapt to mechanical stimuli, and biomechanical analysis suggests that muscle forces play an important role. Thus, resistance training is advocated as a first option for a countermeasure modality. In addition, vibration has certain characteristics (well controllable, rapid stretch-shortening and large number of contractions) that could be of interest. Studies in the past decade have shown that conventional resistive exercise may be sufficient to maintain bone when performed on a daily basis, but not when performed only every other day. Whole body vibration without additional load seems to be ineffective, but it shows good potential, and probably will have a genuine effect upon bone when combined with additional loads in the order of twice the body weight. There is now accumulating evidence to suggest that effective exercises exist to counteract microgravity-related bone loss. At least for bed rest, forceful muscle contractions seem to be a prerequisite. They may be fortified, but probably not replaced, by vibration exposure

Maximizing far-field optical microscopy resolution through selected fluorophore transitions

Stimulated emission depletion (STED) microscopy and related nanoscopy techniques, which utilize a saturable optical transition between a bright and a dark state, overcome the diffraction barrier by confining one of the states to an area smaller than the Airy disk. Scanning this area across the specimen yields subdiffraction images by registering inseparable fluorescent markers sequentially in time. Despite the progress made in nanoscopy so far, maximizing the resolution has been hampered by the efficiency of the utilized optical transition and the photostability of the fluorophores. Here, the optical transition responsible for breaking the barrier was studied in order to maximize its efficiency. For a range of fluorophores (dyes, proteins, quantum dots, color centers) the nature of the responsible process could be clarified. It was also investigated whether heat could serve as an imaging contrast to provide an alternative to fluorescence. This work demonstrates a resolving power of down to 6 nm in unprocessed recordings, corresponding to lambda/135, which is to date the highest obtained in far-field optics. These measurements, which show no sign of photobleaching or blinking, were performed with diamond color centers using STED and ground state depletion (GSD) microscopy

Assessment of vertical treadmill running under different levels of simulated gravity, using a vertical treadmill facility with a subject loading system (Avatar)

Introduction: Prolonged exposure to microgravity during spaceflights leads to severe deconditioning in the physical performance of astronauts that affects dangerously crew health and safety during mission critical maneuvers. To understand the effectiveness of the existing inflight daily countermeasures, treadmill running in simulated microgravity under different levels of adjusted g-load is compared to usual treadmill running on earth. Methods: For purposes of exercise planning onboard the ISS, the objective of this study was to assess the oxygen uptake under using spiroergometric assessment of men and women (n=26, 8 female and 6 male 20- 30 years; 6 male and 6 female 50-60 years) during running on an horizontal treadmill and on a vertical treadmill under different levels of simulated gravity with the Vertical Treadmill Facility (VTF) and Subject loading system (SLS) from the European Space Agency (ESA) and took place in the Physiology Laboratory of the institute of Aerospace Medicine at the Department of Space physiology at the German Space Center (DLR) in Cologne, Germany. After assessing the maximum oxygen uptake using the Bruce-protocol on the horizontal treadmill, an incremental running protocol on both the vertical and horizontal treadmill was performed in randomized order, starting at a speed of 4 kph and increasing every 4 min by 2.5 kph to a maximum of 19 kph. The runs on the vertical treadmill are performed under 0.3g, 0.6g and 1 g of body weight. Results: 26 Subjects were included with a total of 93 runs (9 of 102 runs excluded). The maximum speed was greater for 0.3g and for 0.6g on the vertical treadmill (P < 0.001, see Table above) than on the horizontal treadmill. By contrast, peak oxygen uptake was greater for the horizontal treadmill than for all conditions on the vertical treadmill (P < 0.001), and so was maximal heart rate (P < 0.05). Conclusion: The reduction in peak oxygen uptake on the vertical treadmill was strikingly similar across the three simulated gravity conditions and cannot be explained by inability to run faster. Rather, gravity-related impediment of gas exchange, or impediment of perfusion in horizontal position can be suspected. If this should be the case, then this would constitute a substantial limitation to exercise in space